1. Field of the Invention
This invention relates to interpolation of data as derived from scientific instruments or similar sources. More specifically, the invention relates to time dependent spectroscopy and to spectrophotometry of chemical samples, and to interpolation of chromatographic absorbances in both the time-absorbance plane, and the wavelengthabsorbance plane.
2. Description of the Prior Art
Liquid chromatography is a well known technique for analyzing fluids. As is well known in liquid chromatography, light of varying wavelengths is passed through a sample cell containing the fluid to be analyzed. A detection and measuring device then measures the amount of light that passes through the sample at a variety of different wavelengths. The resulting data is referred to as chromatographic data. The data is typically represented as a chromatogram. The absorbance data of a chromatogram may be written as a function AU (absorbance units)=f (wavelength, time). Thus, the absorbance is a single valued function in the so-called absorbance-wavelength-time space. That is to say the absorbance, wavelength, and time may be plotted as three dimensions in a three dimensional graph.
Polychromatic data, i.e. data taken at various wavelengths, from a liquid chromatography apparatus, is therefore represented as discrete points on the surface of the wavelength, time, absorbance function. Each measured absorbance is determined by a wavelength and a time, that is, AU=f(.omega., t). A high speed scanning absorbance monitor in the liquid chromatographic apparatus typically measures each absorbance point for each wavelength sequentially with an inherent time delay between each point. Thus the absorbance may be mathematically represented as follows: ##EQU1##
The nature of a liquid chromatographic apparatus or any other scientific instrument is that data must be taken over time The result of the time delay between taking of the various data points is that the absorbances at each of the wavelengths are not measured simultaneously. This situation is shown in FIG. 1. For instance, as the concentrations of the chemical compounds in the fluid in the sample change over time, the measured absorbances change. However, there is a problem in that an accurate comparison to produce meaningful results of the absorbances from several wavelengths requires that ideally all of the absorbances be taken at the same time. This ideal situation is shown in FIG. 4. Thus the data in FIG. 4 is shown as being orthogonal to the time axis. The ideal situation is not obtainable in reality in terms of taking actual measurements.
It is therefore desirable to have a method for achieving the elimination of the effect of time delay from the data, so as to provide an accurate representation of the absorbance as a function of wavelength. Only by providing such a representation is it possible to accurately characterize the constituents of the sample which is being tested. The prior art does not permit such an accurate characterization